1,933 research outputs found
Thermal breakdown of coherent backscattering: a case study of quantum duality
We investigate coherent backscattering of light by two harmonically trapped
atoms in the light of quantitative quantum duality. Including recoil and
Doppler shift close to an optical resonance, we calculate the interference
visibility as well as the amount of which-path information, both for zero and
finite temperature.Comment: published version with minor changes and an added figur
Correlated two-photon scattering in cavity optomechanics
We present an exact analytical solution of the two-photon scattering in a
cavity optomechanical system. This is achieved by solving the quantum dynamics
of the total system, including the optomechanical cavity and the cavity-field
environment, with the Laplace transform method. The long-time solution reveals
detailed physical processes involved as well as the corresponding resonant
photon frequencies. We characterize the photon correlation induced in the
scattering process by calculating the two-photon joint spectrum of the
long-time state. Clear evidence for photon frequency anti-correlation can be
observed in the joint spectrum. In addition, we calculate the equal-time
second-order correlation function of the cavity photons. The results show that
the radiation pressure coupling can induce photon blockade effect, which is
strongly modulated by the phonon sideband resonance. In particular, we obtain
an explicit expression of optomechanical coupling strength determining these
sideband modulation peaks based on the two-photon resonance condition.Comment: 10 pages, 6 figure
Spintronics via non-axisymmetric chiral skyrmions
Micromagnetic calculations demonstrate a peculiar evolution of
non-axisymmetric skyrmions driven by an applied magnetic field in confined
helimagnets with longitudinal modulations. We argue that these specific
solitonic states can be employed in nanoelectronic devices as an effective
alternative to the common axisymmetric skyrmions which occur in magnetically
saturated states
Antiferromagnetism in NiO Observed by Transmission Electron Diffraction
Neutron diffraction has been used to investigate antiferromagnetism since
1949. Here we show that antiferromagnetic reflections can also be seen in
transmission electron diffraction patterns from NiO. The diffraction patterns
taken here came from regions as small as 10.5 nm and such patterns could be
used to form an image of the antiferromagnetic structure with a nanometre
resolution.Comment: 10 pages, 7 figures. Typos corrected. To appear in Physical Review
Letter
Effects of frequency correlation in linear optical entangling gate operated with independent photons
Bose-Einstein coalescence of independent photons at the surface of a beam
splitter is the physical process that allows linear optical quantum gates to be
built. When distinct parametric down-conversion events are used as an
independent photon source, distinguishability arises form the energy
correlation of each photon with its twin. We find that increasing the pump
bandwidth may help in improving the visibility of non-classical interference
and reaching a level of near perfect indistinguishability. PACS: 03.67.Mn,
42.65.Lm, 42.50.St.Comment: Replaced with published versio
Theoretical study of angle-resolved two-photon photoemission in two-dimensional insulating cuprates
We propose angle-resolved two-photon photoemission spectroscopy (AR-2PPES) as
a technique to detect the location of the bottom of the upper Hubbard band
(UHB) in two-dimensional insulating cuprates. The AR-2PPES spectra are
numerically calculated for small Hubbard clusters. When the pump photon excites
an electron from the lower Hubbard band, the bottom of the UHB is less clear,
but when an electron in the nonbonding oxygen band is excited, the bottom of
the UHB can be identified clearly, accompanied with additional spectra
originated from the spin-wave excitation at half filling.Comment: 5 pages, 4 figure
Permutation asymmetry inducing entanglement between degrees of freedom in multiphoton states
We describe and examine entanglement between different degrees of freedom in
multiphoton states based on the permutation properties. From the state
description, the entanglement comes from the permutation asymmetry. According
to the different permutation properties, the multiphoton states can be divided
into several parts. It will help to deal with the multiphoton interference,
which can be used as the measurement of the entanglement.Comment: Final versio
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